Whether the flags have retained their red, white and blue glory is another matter. After decades of exposure to heat, cold and light, the flags' colours are likely to have faded to white, Dr Robinson said.

"Personally I was a bit surprised that the flags survived the harsh ultraviolet light and temperatures of the lunar surface, but they did."

US astronauts planted flags on each of the six Apollo landings beginning in 1969 and ending in 1972.

The flag-raising was a symbolic gesture as the US was a signatory to a 1967 UN treaty forbidding nations from claiming territory on the Moon or "other celestial bodies".

Nasa at one point considered planting a UN flag on behalf of humanity but eventually decided to raise only the American flag.